Precursor T lymphoblastic lymphoma / leukaemia

A neoplasm of lymphoblasts committed to T-cell lineage. Most cases involve blood and bone marrow (T lymphoblastic leukaemia, T-ALL), some present with primary nodal or extanodal tissue deposits (T lymphoblastic lymphoma, T-LBL).

Epidemiology

T-ALL is predominantly a disease of adolescents and occurs more commonly in males. T-ALL constitutes ~25% of all cases of adult ALL. T-LBL constitutes ~85% of cases of lymphoblastic lymphoma and most cases are adolescent.

Clinical features

T-ALL usually presents with a leukocytosis and often with a large mass in the mediastinum or elsewhere. There is a relative sparing of bone marrow haematopoiesis. T-LBL often presents with a mediastinal mass, less often with involvement of peripheral lymph nodes, skin,liver, spleen, Waldeyer's ring, CNS or gonads.

Histopathology

Immunohistochemistry

 

immunoreactivity

notes

TdT

positive

nuclear positivity is unique to LBL

CD1a

variable

 

CD2†

variable

 

CD3

usually positive, cytoplasmic

the only marker considered lineage-specific

CD4†

variable

frequently co-expressed with CD8

CD5

variable

 

CD7†

usually positive

 

CD8

variable

frequently co-expressed with CD4

CD10

may be positive

 

CD13

often positive

 

CD33

often positive

 

CD79a

positivity has been observed

12/23 cases positive on frozen section1 

CD117

rarely positive

 

 

†: fresh frozen tissue only

Differential diagnosis

References

World Health Organization Classification of Tumours, Tumours of the haematopoietic and lymphoid tissues, IARC Press 2001.

1Hashimoto, M., Y. Yamashita, et al. (2002). "Immunohistochemical detection of CD79a expression in precursor T cell lymphoblastic lymphoma/leukaemias." J Pathol 197(3): 341-7.

 

This page last revised 16.12.2002.

©SMUHT/PW Bishop